Magnetic field sensors may be used to exploit a wide range of physical phenomena. Applications may range from sensing of the positioning of a moving metallic component in a machine to the detection of very weak magnetic fields produced by biological systems. Current magnetic field sensors, or magnetometers, include inductive pick-up coils, Hall probes, magnetoresistive elements, magneto-optic devices, flux-gates, superconducting quantum interference devices (SQUIDS), and atomic magnetometers. Magnetometers are typically characterized by their sensitivity, vector or scalar operation, bandwidth, heading error, size, weight, power, cost, and reliability.
Two types of highly sensitive magnetometers are SQUIDs and atomic magnetometers. SQUIDs have a high sensitivity, but require cryogenic cooling to operate. Due to the requirement for liquid gases for cooling, SQUIDs are large devices. Unlike SQUIDS, atomic magnetometers can reach very high sensitivity without requiring cryogenics. As such, atomic magnetometers do not have the size limitation of SQUIDs. Atomic magnetometers are used most frequently for the detection of magnetic anomalies produced by metallic objects such as geophysical structures, vehicles, and ships. Some applications for atomic magnetometers may also include, for example, detection of biomagnetic signals, nuclear magnetization, and magnetic particles. However, atomic magnetometers operate by measuring the changes of properties in a particular atomic gas that is contained within a small glass chamber. As such, the robustness of atomic magnetometers is limited.